Electronic devices use voltage regulators to condition voltage and current from a power supply to the proper value needed for their internal components. Generally, a voltage regulator for an electronic device comprises a circuit component that is configured to regulate the voltage fed to the other internal components of the device. For example, the power supply in a desktop computer system typically generates power at a number of different voltage levels. The computer system's voltage regulator functions by generating the different voltages used by different components of the device. For example, complex integrated circuits can require several different voltage levels for several different internal components. For example, a microprocessor can require a certain core voltage (e.g., 1.8 volts), which may be different from memory voltage (e.g., 2.0 volts), or I/O voltage (e.g., 3.3 volts).
For example, with integrated circuit electronic devices, as integrated circuits have become more complex, the demands placed upon the voltage regulator systems have become similarly more complex. For example, in addition to requiring several different voltage levels, these voltage levels need to be changed in accordance with the operating modes of the integrated circuit (e.g., full power, sleep mode, standby, etc.). The voltage levels need be precisely maintained at their specified levels in order to ensure the proper function of the integrated circuit. As the levels of integration increase (e.g., over 100 million of transistors on a single die), integrated circuit devices become more sensitive to glitches, surges, drooping, and the like on the voltage supply levels. Additionally, some types of digital integrated circuit devices are prone to large changes in circuit loading, such as, for example, when a user initiates some new application function or some new data must be processed at high clock frequencies.
Also a common problem is the testing of a circuitry for function in all operating conditions. During validation the circuit's voltage will be changed to test the device under test on the high and low borders of the tolerance band of the regulator (shmoo). Some circuits require this test on all units at production test (margining).
Other challenges to the proper functioning of a voltage regulator system involve the distribution of power efficiently to the millions of transistors of the electronic device. Complex electronic devices employ multiple voltage rails that span large areas of the die to deliver power to the various components of the die.
In attempting to address these challenges, some prior art voltage regulators employ sophisticated and comparatively expensive schemes to provide simultaneous set point adjustment for multiple regulators. For example, some prior art schemes are designed to use two input rails only, and cannot use more than two, which limits their flexibility. Similarly, some prior art schemes provide for only one output rail. This is generally due to limitation that in those cases where more than two output phases are needed, the voltages on the input rails cannot be too far removed from one another (e.g., in phase/amplitude) in order for the multiple regulators to function properly. Thus, a new system is required for adjusting set points for one or more regulators at the same time.